The present invention relates generally to an interface device for a torque and/or rotational control apparatus such as clutches or brakes, and most particularly to an interface disc for a torque and/or rotational control apparatus having greatly increased heat dissipation.
It is a continuous problem to provide clutches or brakes which are efficient, have high ability to transfer the heat energy generated in the engagement process and/or in a constant slipping arrangement, and are easy to maintain and operate. U.S. Pat. No. 4,474,268 shows one type of apparatus designed to solve this problem and particularly is an external, multi-caliper brake arranged to provide controlled torque to a shaft including a hub arranged to be mounted to this shaft. A longitudinally centrally located, internally finned friction disc is in turn mounted to the hub. It can be appreciated that the capacity of the brake is dependent on the dissipation of heat which in turn is dependent upon air flow. The friction disc described provides increased cooling and increased brake efficiency by a finned arrangement. Specifically, the friction disc is formed of two, opposed, interlaced, finned portions to create a serpentine, radial and circumferential air cooling path for the friction disc and provide better heat transfer and increased brake efficiency. Although the apparatus of U.S. Pat. No. 4,474,268 showed a marked increase from prior apparatus in the ability to transfer the heat energy generated in the engagement process, further efforts were continued to improve capacity and efficiency including the utilization of cooling enhancing devices such as of the type taught in U.S. Pat. Nos. 4,561,522 and 4,846,315.
To optimize thermal dissipation, manufacturers ordinarily design friction discs that will rotate in a predicted direction. This predicted direction will allow for designs that optimize the flow of air through the fins. Using design concepts similar to those used by turbines drawing in air and then accelerating it radially outward, designers have developed friction discs with curved, separated, angled, and closed bodies to optimize the transfer of energy from the disc surfaces to the air.
The thermal efficiency of these turbine friction discs has excelled greatly due to techniques in CFD (computational fluid dynamics). By using computers to test models for air volume, speed, and turbulence, great strides have be made in the prediction of thermal performance. U.S. Pat. No. 5,242,036 shows one type of friction disc with angled fins designed to optimize the flow of air and which has enjoyed considerable commercial success.
However, prior flow optimizer friction discs have a downside. Although the efficiency is increased in one direction, when the friction disc is rotated in the opposite direction, the efficiency is greatly reduced. The movement of air inside the fins is retarded. This unwanted product of design efficiency forces the manufacturer to design two versions of the same rotor, one for each direction of rotation.
Thus, even with the development of friction discs having enhanced capabilities, the need and problem continue to provide friction discs with even greater ability to transfer the heat energy generated in the engagement process and/or in a constant slipping arrangement and which overcome the deficiencies of the prior art.